| Summary: | 博士 === 國立成功大學 === 航空太空工程學系 === 88 === \centerline{\aaab Nonlinear H$_\i$ Guidance Law Design}
\centerline{\aaab for Homing Missiles}
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\noindent {\ab Student : Hsin-Yuan Chen}
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\noindent {\ab Advisor : Ciann-Dong Yang}
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\centerline{\ab ABSTRACT}
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\quad This dissertation is dedicated to investigating the design and analysis of nonlinear H$_\i$ guidance law for homing missiles. This investigation has not been considered before in the international literature. The theoretical background of this dissertation is based on the dissipative theory from which the Hamilton-Jacobi Partial Inequality(HJPDI) associated with the missile guidance problem is derived, and a set of particular solutions of HJPDI is found analytically . From these particular solutions, we then construct nonlinear H$_\i$ guidance law in a closed form. Though the implementation of nonlinear H$_\i$ guidance law does not require the information of target acceleration, it can ensure acceptable interceptive performance for arbitrary target maneuvers. Proposing the concept and synthesis of nonlinear H$_\i$ guidance design are the first contribution of this dissertation.
However, the robustness of H$_\i$ guidance law against arbitrary target maneuvers inevitably results in a somewhat conservative design, since increasing robustness alone may sacrifice performance to some extent. To remedy this drawback, we add the H$_2$ criterion, which is a good measure taking care of missile performance, into the established H$_\i$ robust guidance design. This combination is called mixed H$_2$/H$_\i$ guidance law which is a compromising guidance law between robust H$_\i$ guidance and the conventional LQG (H$_2$) guidance. Nonlinear mixed H$_2$/H$_\i$ guidance benefits from the advantages of both H$_\i$ guidance and LQG guidance, and is the second contribution of this dissertation.
The design of robust guidance laws assumes that target maneuver is an unpredictable disturbance. But in practice, target''s acceleration can be estimated to certain accuracy by missile on-board computer using measurement data from seeker. To reflect this practice consideration, we incorporate the estimated target information into the synthesis of robust guidance law by adaptively tuning the navigation gains in the derived H$_2$/H$_\i$ guidance law according to the real-time estimation of target acceleration. The resulting design is called nonlinear adaptive H$_2$/H$_\i$ guidance law which combines the advantages from adaptive guidance design and robust guidance design, and which is the third contribution of this dissertation.
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